/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package io.github.shengjk.udf;


import org.apache.commons.lang3.time.FastDateFormat;
import org.apache.flink.table.functions.ScalarFunction;

import java.util.Date;
import java.util.GregorianCalendar;
import java.util.Objects;

/**
 * @author shengjk1
 */
public class MillisecondsToDateStr extends ScalarFunction {

	private static final long serialVersionUID = -6307408162865481215L;

	public String eval(Long milliseconds, String format) {
		if (Objects.isNull(milliseconds)) {
			return null;
		}
		GregorianCalendar gc = new GregorianCalendar();
		Date dat = new Date(milliseconds);
		gc.setTime(dat);
		FastDateFormat formatDate = FastDateFormat.getInstance(format);
		return formatDate.format(gc.getTime());
	}
}
